Installation for coating paper and like sheets with varnish and the like



INSTALLATION FOR COATING PAPER AND LIKE Dec. 5, 1967 T. B. BUSH ETAL3,356,064

- SHEETS WITH VARNISH AND THE LIKE Filed Feb. 7, 1966 8 Sheets-Sheet 1F/G IA INVENTOR:

QZ M Z Hr M r Dec. 5, 1967 Filed Feb. 7, 19 66 INSTALLATION FOR COATINGPAPER AND LIKE SHEETS WITH VARNISH AND THE LIKE T. B. BUSH ETAL 8SheetsSheet 2 INVE NTOR:

BY MAMQ.

Dec. 5, 1967 T. B. BUSH ETAL INSTALLATION FOR COATING PAPER AND LIKESHEETS WITH VARNISH AND THE LIKE 8 Sheets-Sheet 5 Filed Feb. 7, 1966INVENTOR:

THOMAS 8.305'1'4 HGNRYN'BUSH Dec. 5, 1967 T. B. BUSH ETAL INSTALLATIONFOR COATING PAPER AND LIKE SHEETS WITH VARNISH AND THE LIKE 8Sheets-Sheet 4 Filed Feb. 7, 1966 INVENTOR: THOMRS Bfius/I 4 HEuRYN-BUSHDec. 5, 1967 T. B. BUSH ETAL INSTALLATION FOR COATING PAPER AND LIKESHEETS WITH VARNISH AND THE LIKE 8 Sheets-Sheet 5 Filed Feb. 7, 1966INVENTOR: THOMAS B-BUSH4 new/2y /v. 1305 BY I d LMAQM 4.

R-rro a 8 Sheets-Sheet 6 l IIHR SHEETS WITH VARNISH AND THE LIKEINSTALLATION FOR COATING PAPER AND LIKE Dec. 5, 1967 Filed Feb. 7, 1966INVENTOR: um/m5 3.30s; u'elvfiwv-fi'usl/ M ume? E BY am 4.

)IllIlIlHIIK J l Dec. 5, 1967 BUSH ETAL 3,356,064

INSTALLATION FOR COATING PAPER AND LIKE SHEETS WITH VARNISH AND THE LIKEFiled Feb. 7, 1966 8 Sheets-Sheet 7 INVEINTOR: THOMAS E. su'sHq H NRy/V-50s fMj J- M Dec. 5, 1967 T. B. BUSH ETAL 3,356,064

INSTALLATION FOR COATING PAPER AND LIKE SHEETS WITH VARNISH AND THE LIKEFiled Feb. '7, 1966 8 Sheets-Sheet 8 THOMA B-BusH 1 HENRY N- gas BY IATTORN INVENTQR:

United States Patent 5 Claims. (Cl. 118-66) ABSTRACT OF THE DISCLOSUREAn installation for applying coating material to separate paper sheetscomprising a coating machine into which the separate sheets are passedbetween a backing cylinder and a coating applying means together with anendless gripper conveyor for taking successive coated sheets into anoven dryer from which the dried sheets are conveyed to a cooling tunnel.

This invention relates to an installation for applying liquid varnish orlacquer, plastic lacquer or like rapiddrying coating materials to thesurface of paper or like sheets, that is separate sheets such as are fedinto a coating machine by releasable grippers, as opposed to longlengths of paper or the like which can be drawn through the machine froma feed roll of the paper.

The present invention concerns an installation which embodies a coatingmachine constructed and arranged to operate as disclosed in one or otherof the specifications of our British Patents Nos. 852,489 and 950,908,current series in which machine the separate sheets are passed betweenthe backing cylinder and a varnish-applying roller with the latterrotating in a reverse surface direction relative to that of thecylinder. This reverse-roller coating process as applied to separatesheets enabled a thicker coating and one with a much glossier finish tobe produced without the ribbing or longitudinal marking of the papersurface which usually resulted when attempts were made to apply morevarnish with conventional machines.

The varnished sheets produced by the machines of our said prior patentshave an extremely high quality finish and a thicker coating than usualand consequently call for improved techniques in their handling anddrying on leaving the coating machine. It is an object of the presentinvention to provide an improved installation for this purpose.

The installation according to the invention includes a coating machineof the indicated kind, means for feeding separate sheets to the cylindergrippers of such machine, an endless take-off gripper conveyor fortaking the successive coated sheets from said cylinder and conveyingthem by its lower stretch, a tunnel oven or dryer having a series ofradiant heaters or having hot air blowing provision, an endless ovengripper conveyor for taking the successive sheets from said take-01fconveyor and conveying them on its upper stretch through said oven, acooling tunnel having an endless cooling gripper conveyor for taking thesuccessive sheets from said oven conveyor and conveying them by itslower stretch through the cooling tunnel supported on an openwork apron,and means for delivering said sheets from said cooling conveyor.

The whole installation is arranged to be driven and controlled so as toensure proper drying of the coated sheets before they are stacked orpiled together, and may include manual or automatic control mechanismand devices to achieve this purpose. For example, they may behermostatic and/ or timer control of the oven tempera- 3,356,064Patented Dec. 5, 1967 ture which may vary in different parts of theoven, although the sheets will travel through the installation at aspeed governed by that of the coating machine. This speed can be highcompared with conventional machines due to the positive gripper controlon the sheets throughout, and due to the efiicient and uniform dryingand subsequent cooling. The cooling is preferably produced by air jetsissuing from two sets of cooling pipes above and below the sheets.

Whilst radiant heaters such as those of the ceramic type arranged abovethe travelling sheets are very suitable for use in the tunnel oven ordryer of this invention and their use is herein described andillustrated by Way of example, it is to be understood that othersuitable forms of drying provision may be used. In particular, it may befound more advantageous to use what is termed in the art high velocityair blast drying. This system is well known in the paper conditioningtrade for treating continuous paper webs and consists in blowing heatedair by a high velocity in downwards over the travelling sheets andwithdrawing and recirculating the air.

In order that the invention may be fully and clearly comprehended, thesame will now be described with reference to the accompanying drawings,which illustrate one form of installation and wherein:

FIGURES 1A, 1B and 10 represent jointly a schematic side elevation ofthe installation showing the general layout;

FIGURE 2 represents on a larger scale a side elevation of the coatingmachine, the takeoff conveyor and the adjacent receiving end of the ovenconveyor;

FIGURE 3 represents in end elevation, as seen in the direction of arrowX in FIGURE 1A, the driving connections to the coating machine andtake-01f conveyor, other features irrelevant to the driving means beingomitted;

FIGURE 4 shows an end elevation (with portions in section) of thedriving and control mechanism for the receiving end of the ovenconveyor;

FIGURE 5 represents a vertical section, taken mainly on the line VV inFIGURE 4, of the oven conveyor at its receiving end, showing the meansfor gripping and supporting the coated sheets; v

FIGURE 6 is a section taken on the line VIVI in FIGURE 5 showing howsaid means for supporting the 45' sheets is mounted on the ovenconveyor;

FIGURE 7 is an enlarged sectional view of one of the gripper devices onthe take-off conveyor; and

FIGURE 8 represents a plan of the cooling and delivery end of theinstallation shown in FIGURE 1C, the overhead exhaust ducting beingomitted.

Referring first to the general lay-out of the installation asillustrated by FIGURE 1, a sheet-feeder A is arranged to feed the papersheets one at a time to the cylinder grippers of a coating machine B.The sheets are then transferred to the grippers of a take-off conveyor Cwhich in turn transfers them to the grippers of an oven conveyor whichcarries them through a tunnel dryer or oven D. On emerging from the oventhe sheets are again transferred to the grippers of a cooling conveyorwhich carries them through a cooling tunnel E and releases them to asheet deliverer F. These parts of the installation will now be describedin order.

The sheet feeder A may be of any suitable kind but is illustrated as apile feeder having a frame 1, a table top 2, a sheet platform 3 whichcan be raised progressively by chains or cables 4 carried over wheels 5to maintain the top sheet of the pile at the table level, and meansdriven by a belt 6 for feeding the sheets S successively atpredetermined intervals over support table 7 to the coating machine B.Such a sheet feeding machine is well known and needs no furtherdescription.

The coating machine B (or varnisher as it will be called) has a frame 8supporting a rotatable cylinder 9 between the ends of which is carried arockable gripper shaft 10 (see FIGURE 2). This shaft carries a series ofgrippers 11 spaced apart along the shaft and as the cylinder rotates inthe direction of the arrow the grippers are caused by known cammechanism to grip the leading edge of the sheet on table 7 and carry itpast the varnish trough 12 where the contra-rotating varnish-applyingroller 13 coats it with varnish. When the gripper bar 10 reaches theposition indicated in dot-and-dash lines in FIGURE 2, the grippers arecaused to release the sheet in known manner and its leading edge issimultaneously gripped by another .set of grippers on the take-offconveyor C.

This conveyor as shown in FIGURES 2 and 3, is of the endless chain typehaving two chains 14 carried round wheels 15, 16 supported in a casing17. This conveyor carries two transverse gripper bars 18 (omitted fromFIG- URE 3) and as shown in FIGURE 7 each bar has a rockable shaft 19 onwhich are secured a series of grippers 20 which are spaced along theshaft so as to correspond in position with the spaces between thegrippers 11 on the varnisher cylinder. The shaft 19 carries an arm 21with a runner 22 arranged to engage an adjustable timer cam 23 to closethe grippers towards a rubber or like pad or pads 18X so as to grip theleading edge of the sheet S as it is released by the grippers 11 andtrail the sheet along the openwork bottom of casing 17. A similar timercam (not shown) opens the grippers to transfer the sheet from the bottomstretch of the conveyor C to the top stretch of the oven conveyor.

The means for driving the mechanism so far described is as follows. Anelectric motor 24 drives, through suitable speed-varying mechanism apulley 25 which through belt 26 and pulley 27 drives shaft 28, and thisshaft transmits the drive through pulley 29, belt 30 and pulley 31 toshaft 32 on which is secured a pinion 33 driving gear wheel 34 securedon the shaft 35 of the varnisher cylinder 9. The belt 6 for driving thesheet feeder is also driven from shaft 32. The belts and pulleys will beof the positive drive type, or chains and chainwheels may be usedinstead, to ensure that the parts are driven at definite known speedsbecause this is essential to enable the take-off conveyor to co-operateaccurately with the varnisher roller and the oven conveyor in order toensure a smooth passage of the coated sheets.

The oven D is of thetunnel-dryer type and consists of a long casing 36(say long) with side channel members 37 mounted on legs 38 and havingsets of ceramic or other radiant heating elements 39 supported above theoven gripper conveyor. These elements may be of different power indifferent sections of the oven. The conveyor consists of two endlesschains 40 carried round pairs of wheels 41, 42 and supported along theirlengths in channel or other guides, this arrangement being well knownand requiring no further description. These chains carry between them aseries of gripper bars 43, and each gripper bar has pivotally mountedupon it a row of grippers 44, these grippers being spaced apart so as toco-operate with the grippers 20 on the take-off conveyor and to actbetween the latter during transfer of each sheet to the top stretch ofthe oven conveyor. The grippers are opened and closed by devices (notshown) similar to the timer cam 23 described with reference to thetake-off conveyor C.

We have found that in transferring thesheets from the grippers of thetake-01f conveyor, which runs at the same surface speed as that of thecylinder of the coating machine, to the grippers of the oven conveyor,which runs at a lower speed than that of the take-off conveyor, it isdifiicult to ensure uniformity in the amount of sheet edge which isgripped by the oven grippers. The sheet edges each have an uncoatedstrip which may be Wide and on which the gripper should bite, but owingto the difference in speeds of the two conveyors and the momentum of thesheets at the moment of transfer the oven grippers may grip beyond theuncoated strip. This would result in wet coating material beingtransferred onto the gripper faces, thus spoiling the sheets andnecessitating cleaning of the gripper faces.

In order to overcome this difficulty each gripper bar 43 is fitted onits rear face with a number of stops 45 located (say) back from thegripper edges so that the front edges of the sheets, once they haveengaged the stops, will not move relatively thereto when being grippedand will only begripped by their uncoated edges. The stops are suitablyspaced along the bars, say eight on each bar, and each one is preferablylocated close beside a gripper to minimise undesirable movement of thesheet edge against the stops during gripping and releasing of thesheets. If desired these stops may be faced with or formed from a softermaterial than metal to reduce the chance of their marking the frontedges of the sheets.

The manner in which the sheets are supported when being conveyed throughthe oven is also very important for high quality products. If the sheetsare gripped at the leading edge and allowed to trail along a smoothsheet metal floor, they may dry with an undesirable curvature, the metalfloor may become overheated, and (most important) some parts of thesheets will be supported nearer to the overhead heaters than others anduneven drying will result.

In order to overcome this difficulty, we provide a series of flexibleaprons 46 supported from the chains 40 between adjacent gripper bars 43so as to extend substantially horizontally and to form supports for thesheets during their passage through the oven. These aprons may be ofhessian or other fibrous fabric or of any other flexible material whichwill Withstand th heat, and are preferably of openwork structure toreduce their tendency to overheating. These aprons can be quite cheapand can easily be attached at their front and rear edges by passing rods47 through the looped ends of the aprons and securing the rod ends tobrackets 48 mounted on the chains 40 as clearly shown in FIGURES 5 and6, so that the aprons extend approximately in line with the grippingsurfaces of the bars 43 and grippers 44. By thus supporting the sheetssubstantially parallel to the plane of the heaters 39 a much moreuniform drying effect may be obtained. Rollers 49 mounted between theconveyor wheels 41 and 42 (see FIGURE 5) control the aprons at each endof the conveyor.

The cooling tunnel E (FIGURES 1C and 8) has a casing not shown in thedrawings and through this extends a cooling conveyor which may be of asimilar construction to that of the take-off conveyor C but much longer.Two endless chains 50 are carried around wheels 51, 52 mounted betweenthe ends of frame members 53, and-these chains carry sets of grippers ongripper bars 54 (omitted from FIGURE 8) which may be similar to those onthe oven conveyor and which grippers are arranged to be opened andclosed also in similar fashion. The grippers on the bottom stretch ofthe cooling conveyor drag the sheets by their leading edges across astationary openwork apron 55.

Within the cooling tunnel and extending across and a short way above thebottom stretch of the conveyor are banks of cooling pipes 56, and justbelow this stretch are further banks of cooling pipes 57, all thesepipes being perforated at closely spaced intervals with holes of asuitable size or of different sizes (e.g. diameter spaced at 1" centres)arranged to direct jets of cooling air onto the passing sheets S atsuitable angles and with suitable force, but not sufiicient todisarrange the sheets nor to disturb the smooth surface of the coating.Each bank of pipes is secured to a manifold 58 which communicates by aduct 59 having an adjustable bafiie 60 with a main duct 61 to whichcooling air is supplied by a fan 62 driven by a motor 63. Air at ambientroom temperature is preferred for cooling, but if desired the air fed topipes 56, 57, may be drawn through a cooling device of any suitablekind.

In order to enable the cooling jets to be directed against the sheets atthe angle best suited to the nature of the sheets and the coating mediumbeing used at any particular time, the pipes 56, 57 ar preferablyattached to the manifolds by flexible or rotary couplings which willenable some or all of the pipes to be turned through desired angles, andthese couplings will be easily disconnectible to enable other pipes withditferent perforations to be substituted. This arrangement inconjunction with the speed of the conveyor will enable a very accuratecontrol to be exercised over the degree and nature of the coolingaction, and has an important bearing on the quality of the surfacefinish of the sheets.

The sheet deliverer F may be of any suitable kind but is illustrated asa pile deliverer operating in the reverse way to the feeder A. It has aframe 64 supported on legs 65, and a receiving table 66 can be slowlylowered as the dried sheets are deposited upon it successively to form apile in the normal manner of such deliverers. The lowering mechanism incasing 67 can be of any suitable kind and can be driven independently ofthe rest of the installation at a predetermined speed or can be drivenfrom the cooling conveyor. The frame and drive casing are omitted fromFIGURE 8 for clarity, but FIGURE 1C shows how the cooling conveyor 50extends over the deliverer F and draws each sheet in turn off the end ofthe apron 55 onto the table 66 and then releases it.

The casings of the take-off conveyor and oven conveyor are provided withoutlet ducts 94 having separately adjustable baffles 95 andcommunicating with a common trunking 96 leading to an extraction fan 97driven by an electric motor 98, the fan and motor being mounted on asupport 99 upon the frame members 53 of the cooling conveyor. Thisextraction system removes fumes from the neighbourhood of the oven andtake-off conveyors and, if so arranged, of the varnisher.

The main drive for the installation is from motor 24 through gear 34 togear 70 secured on the shaft of wheels which drive the take-01f conveyor(see FIGURE 3). Wheels 16 of this conveyor then drive through spur gears71, '72 and 73 a spur gear 74 which, during normal running of theinstallation, is connected to drive the shaft on which are secured thewheels 41 carrying the oven conveyor 40. This conveyor in turn, throughits wheels 42 and a train of spur gears 75, 76, 77, 78 (shown only inFIGURE 1C), drives the cooling conveyor 50 at the same speed. Thus thetravelling movements of the grippers on the three conveyors arecorrectly synchronised.

It has been mentioned above that the oven conveyor 40 runs at a lowerspeed than that of the take-off conveyor 14, the distance betweenadjacent gripper bars being different in the two cases to permit thetransfer of sheets to take place. This differential speed is verydesirable because on the conveyor 14 the successive sheets are (say) 30"apart as they come off cylinder 9, whereas it is desirable that theyshould follow one another closely through the oven to achieve themaximum drying time within a minimum length of oven.

A further feature of the driving and controlling mechanism of theinstallation is illustrated particularly in FIG- URES 1, 2 and 4. Thegear 74 is freely mounted about the shaft on which conveyor wheels 41are secured but is normally connected thereto by a dog clutch 80 keyedor otherwise slidably secured to the shaft to rotate with it, the dogteeth being adapted to engage in recesses in the face of gear 74. Theclutch is always drivably connected to a bevel gear 81 in engagementwith a bevel gear 82 on a long drive shaft 83 which is supported atintervals from the channel members 37 and which carries at its other enda bevel gear 84 engaging a bevel gear 85 secured on the shaft of theconveyor wheels 42. The projecting end of drive shaft 83 is coupledthrough a one way clutch of any suitable kind and through pulleys 86, 87and belt 88 with an electric motor 89. This motor can be started andstopped by operation of a switch 90 actuated by a pivoted handle 91which is connected through rod 92 to a clutchoperating lever 93.

These driving connections provide a positive drive for both ends of theoven conveyor which is very desirable in view of its length, but it alsoacts as an auxiliary drive for the purpose now to be described.

When starting up the installation, the auxiliary drive motor 89 and theoverhead heaters 39 would be switched on first, with clutch disengagedand switch 90 held on by handle 91. The oven conveyor must be keptmoving to prevent overheating of it and, in particular, of the aprons46. When the oven has reached the predetermined temperature, the maindrive motor 24 is started to drive the feeder, varnisher and take-offconveyor. The oven conveyor is then coupled to the main drive byoperating lever 91 which through switch 90 stops the motor 89, theclutch 80 acting to synchronise the movements of the two conveyors toensure correct co-operation between their two sets of gripper bars.

When stopping the installation, the auxiliary drive for the ovenconveyor and cooling conveyor is first started by operating handle 91and then the main drive motor 24 is stopped; or if desired, handle 91may be arranged to actuate a further switch to stop and start motor 24,in which case stopping of the varnisher would automatically causestarting of the auxiliary drive. In any event, the auxiliary drive formsa safety device to ensure that the oven conveyor will continue tooperate until all the sheets S are delivered from the oven, thuspreventing possible damage to them by overheating and avoiding firerisks. It will also be arranged by suitable control devices of knownkind to ensure that the oven conveyor keeps moving as long as theheaters are operating.

It will be noted that fire risks are minimised by the provision of theabove-mentioned auxiliary drive arrangement, and also by the use ofceramic heaters located only above the travelling sheets whereby thesheets cannot fall on the heaters.

Whereas high velocity air blast drying could not previously be used fortreating separate paper or like sheets in a tunnel oven or dryer becausethe blast would disturb the sheets and damage them, this system can beused in the present invention because of the novel manner in which thesheets are supported on the flexible aprons so as to be undisturbed bythe downward blast. Also this drying system would further reduce thefire risks and would enable a shorter oven to be used owing to thegreater drying efficiency.

Not only will the installation handle the full-width sheets for whichthe varnisher is designed, but the positive gripper control on all theconveyors enables narrower sheets to be handled in two or more streamsside by side, the feeder and deliverer being provided with suitableattachments for this purpose as will be clear to those skilled in theart.

Whilst the hereinbefore described embodiments of the invention have beenmentioned merely by way of example, it is to be understood that othersuitable embodiments may be evolved for carrying out the invention andthat protection is hereby claimed for all such embodiments within thescope of the appended claims.

We claim:

1. An installation for applying liquid varnish and like rapid-dryingcoating materials to the surface of a sequence of separate andunconnected paper and like sheets, which includes the combination of acoating machine having a cylinder with grippers thereon, means adjacentsaid cylinder for applying coating material, means for feeding separatesheets to said cylinder grippers, an endless take-off gripper conveyorfor taking the successive coated sheets from said cylinder and conveyingthem by its lower stretch, a tunnel oven dryer having heated dryingprovision, an endless oven gripper conveyor for taking said successivesheets from said takeoff conveyor and conveying them on its upperstretch through said oven, a cooling tunnel having an endless coolinggripper conveyor for taking the successive sheets from said ovenconveyor and conveying them by its lower stretch through said coolingtunnel,

means for delivering said sheets from said cooling conveyor, and meansfor driving and controlling said feeding means, said coating machine andall said gripper conveyors.

2. An installation including the combination called for in claim 1, andwherein said driving means includes a common power means for drivingsaid coating machine and all said conveyors and also includes anauxiliary power means for driving said oven conveyor and coolingconveyor when said coating machine and take-off conveyor have beenstopped, there being means for starting said auxiliary driveautomatically when said common drive is stopped, and means forautomatically synchronising the travelling movements of the grippers onthe take-off conveyor and oven conveyor when these two conveyors arebeing connected to be driven from said common driving means.

3. An installation including the combination called for in claim 1, andwherein said oven conveyor carries transverse gripper bars each with aseries of grippers thereon and also carries between each pair ofadjacent gripper bars a flexible apron arranged to support a travellingcoated sheet thereon in a substantially horizontal position, there beingguiding means for controlling said aprons at each end of said conveyor.

4. An installation including the combination called for in claim 3 andfurther including sets of abutments on and spaced along each of saidgripper bars and spaced rearwardly from the gripper edges so as toensure that each sheet is gripped only by the uncoated strip along itsleading edge.

5. An installation including the combination called for in claim 1 andincluding in said cooling tunnel means for directing a multiplicity ofjets of cooling air against the upper and lower surfaces of thetravelling sheets and means for varying the angle of impingement of saidjets upon said sheets.

References Cited UNITED STATES PATENTS 3/1951 Belluche et al. 11887/1966 Dickerson 1l8209 X

1. AN INSTALLATION FOR APPLYING LIQUID VARNISH AND LIKE RAPID-DRYINGCOATING MATERIALS TO THE SURFACE OF A SEQUENCE OF SEPARATE ANDUNCONNECTED PAPER AND LIKE SHEETS, WHICH INCLUDES THE COMBINATION OF ACOATING MACHINE HAVING A CYLINDER WITH GRIPPERS THEREON, MEANS ADJACENTSAID CYLINDER FOR APPLYING COATING MATERIAL, MEANS FOR FEEDING SEPARATESHEETS TO SAID CYLINDER GRIPPERS, AN ENDLESS TAKE-OFF GRIPPER CONVEYORFOR TAKING THE SUCCESSIVE COATED SHEETS FROM SAID CYLINDER AND CONVEYINGTHEM BY ITS LOWER STRETCH, A TUNNEL OVEN DRYER HAVING HEATED DRYINGPROVISION, AN ENDLESS OVEN GRIPPER CONVEYOR FOR TAKING SAID SUCCESSIVESHEETS FROM SAID TAKEOFF CONVEYOR AND CONVEYING THEM ON ITS UPPERSTRETCH THROUGH SAID OVEN, A COOLING TUNNEL HAVING AN ENDLESS COOLINGGRIPPER CONVEYOR FOR TAKING THE SUCCESSIVE SHEETS FROM SAID OVENCONVEYOR AND CONVEYING THEM BY ITS LOWER STRETCH THROUGH SAID COOLINGTUNNEL, MEANS FOR DELIVERING SAID SHEETS FROM SAID COOLING CONVEYOR, ANDMEANS FOR DRIVING AND CONTROLLING SAID FEEDING MEANS, AND COATINGMACHINE AND ALL SAID GRIPPER CONVEYORS.